The invention relates to friction clutches and in particular to dual friction clutches.
A dual friction clutch, which is employed for connecting a driving member to either one or both of two driven members or of disconnecting both driven members from the driving member is typically used in an agricultural tractor or in other situations where a main vehicle drive and a power take off (PTO) are required from the main engine. A typical dual clutch incorporates a single release mechanism and is such that when the release mechanism is fully released a driving connection is established from the driving member to both driven members. As the release mechanism is operated, first the driven member associated with the main vehicle drive is released and subsequently the driven member associated with the power take off is released.
A typical dual clutch incorporates two independent pressure plates which engage driven members against friction faces of the driving member and employ two independent springs or sets of springs to act between the clutch cover and the associated pressure plate to provide clamping loads on the driven members. Dual clutches of this kind tend to occupy a large space in a situation where a vehicle designer would like to be able to reduce the space required. Another disadvantage of a conventional dual clutch is that the release load required on a driver operated foot pedal tends to be excessive if the release travel is maintained within reasonable limits.
An object of the invention is to provide an improved dual clutch which can be made compact and can be made to avoid excessive release travel.